In various situations it may become desirable to warm or heat a body portion of a subject on a relatively rapid, but controlled basis, in order to achieve a predetermined level of warming. While various methods and approaches have been available for such purposes, they have tended to be slow, ineffective or not readily controllable as to the degree of warming or heating achieved. It has also been difficult to control the positional application and effects to selected areas, relative to other body portions. Certain other mediums, such as x-rays, are difficult to contain and potentially injurious to operators and patients. Also, many potential approaches and mediums capable of providing body heating are not amenable to heating of a subject's entire or substantially entire body on a readily controllable basis.
The microwave body heating system disclosed in U.S. Pat. No. 5,922,013 uses two or more focused waves of microwave energy. A fan wave or transversely scanned wave is directed to a narrow transverse section of a subject's body. The transversely scanned or fan wave is moved longitudinally down the body in a controlled sequential incremental manner. Scanning times, patterns and radiated power levels are controlled in predetermined or monitored formats to achieve desired levels of heating of an entire body or localized area. Microwave frequency energy is provided by two or more magnetron type devices in a variably positionable microwave power assembly, which is longitudinally scanned under control of a robotic motor. The complete disclosure of U.S. Pat. No. 5,922,013 is hereby incorporated by reference.
Modem microwave systems for therapeutic use are based on a magnetron element for generation of microwave energy. A magnetron is a high-powered vacuum tube that generates coherent microwaves. A magnetron works by providing a plurality of resonating cavities arrayed around a central cavity that act to induce a resonant field within the central cavity, which can be directed into a waveguide for delivery and use. By default, the waveform that emits from a magnetron is approximately sinusoidal. Investigators have experimented with a variety of frequencies to kill microorganisms. Work by Dr. Royal Raymond Rife and others showed that audio frequencies with a square wave could be therapeutically effective.
Notwithstanding the therapeutic advancements described in U.S. Pat. No. 5,922,013, the need continues to exist for systems and methods of treatment that optimally apply microwave therapies in a non-injurious manner. This need proves particularly acute in the treatment of illnesses such as tuberculosis and lung cancer, where treated lung cells are temperature-sensitive and can prove to be particularly susceptible to microwave heating.